ARCHIVED - Proximity Chat - Campaign

Pardon me if this has been addressed, but I seemed to have trouble hearing other players that were around me in my Campaign missions that were not part of my party/Fireteam when I launched the game. If it was supposed to work, it was not for me.
It would be a great feature to enable some sort of proximity chat system for the Campaign so that as you approach other players in the open-world Campaign, you can hear them and communicate, and choose to keep playing together, etc.
That's my only piece of feedback from the beta that I would find useful for the final release.
Cheers